Transmission of magnetic stripe data has been done primarily by swiping a magnetic stripe card against a magnetic stripe reader (MSR) to enable payment, identification (ID), and access control functions. Mobile wallet applications on smartphones and tablets have had difficulty interacting with existing merchant point of sale (POS) devices or other devices with MSRs. Contactless reader enabled POS terminals (typically using, for example, an ISO-14443 standard) are not ubiquitous to accept contactless or near field communications (NFC) payments. It would be expensive and would take time to replace the millions of merchant POS devices (or door locks) that only accept magnetic stripe cards, just to interact with NFC phones or other transmission means like barcodes.
In recent years devices, systems, and methods have been developed that included a magnetic stripe capture, storage and transmission device for use in conjunction with a mobile wallet application to capture, store and transmit magnetic stripe card data to merchants' conventional point of sale (POS) terminals and other devices with magnetic stripe readers (MSRs) or checkout systems, in physical and virtual environments. These systems provide a convenient payment experience for consumers, a secure transaction for merchants, and in some cases additional data to be transmitted to a MSR for the purpose of loyalty, identification (ID), or access control.
One system developed by LoopPay Inc of Burlington, Mass. for securely capturing, storing and transmitting magnetic stripe payment card data includes a mobile communication device and mobile application, and a magnetic stripe transporter dongle. The magnetic stripe transporter dongle includes a microprocessor, magnetic field transmitter which includes a driver and an inductor that can generate varying magnetic fields, a battery, a charging circuit, a magnetic stripe reader (MSR), a memory means or secure element, an audio jack interface, and a communication interface (for example, a USB interface, a 30pin or 9pin Apple interface, a Bluetooth interface, etc.) working in conjunction with a consumer mobile device and wallet application for capturing magnetic stripe card data, storing the data securely, and transmitting such data to merchants' point of sale (POS) or checkout systems, in the physical and virtual environments.
The Magnetic Secure Transmission (MST) technique magnetically couples simulated magnetic stripe data into a POS magnetic stripe reader (MSR) 101 from a distance of 30 to 40 mm. An alternating polarity magnetic field 102 is generated by driving alternating polarity current through a suitably designed inductor. The MSR head, which contains an inductor, picks up the magnetic pulses and converts them to voltage pulses, which in turn are decoded by the reader circuit and terminal logic. This is schematically shown in FIG. 1.
However, in real life, inductors, including NFC inductors, do not have isotropic fields. Flat inductors, for example, tend to have doughnut shaped fields. Other inductors generate different field shapes.
The overlapping field patterns of the MST transmitter inductor and the reader head inductor result in one or more nulls: narrow areas where no signal transfer takes place. Depending on the inductor topology, these nulls can be either on the center-line of the reader head, or along the edges off to the sides. Nulls affect the reliability of card data transmissions. While users quickly learn in which position their LoopPay device works best, some inconvenience and the need for two or three tries results at times. When MST is integrated into a smart-phone, which is larger than a LoopPay device, precise placement is less likely and therefore first-time MST transmission success rate suffers.